Oxytocin is a neuroendocrine peptide originally known for its role in mating and reproduction and more recently popularized among scientific and lay audiences for its seemingly broad-reaching effects on social cognition. Often touted as the love hormone, oxytocin influences how we attend to, process, and respond to emotionally- and socially-relevant stimuli, which, in turn, affects how we cooperate, trust, and communicate with others. It is therefore not surprising that clinicians have begun administering pharmaceutical oxytocin to patients with certain psychiatric disturbances, including autism, schizophrenia, and depression, with the goal to improve their emotional well-being and quality of social relationships. The fact that exogenous oxytocin shows therapeutic effects for such individuals may, however, give a false impression that oxytocin is universally beneficial for the general population. Indeed, there is an emerging literature to suggest that oxytocin administration can worsen psychosocial adjustment in healthy adults, which has led to the speculation that high oxytocin levels promote a maladaptive hypersensitivity in individuals who are already emotionally attuned. Such differential outcomes may reflect pre-existing, inter-individual differences in the endogenous oxytocin system and/or presence of trait-like contextual factors that moderate the behavioral effects of oxytocin. However, we know little about the psychosocial correlates of naturally-occurring oxytocin levels or how such levels might fluctuate across adulthood or as a function of sex. Similarly, we know little about the degree and nature of influence of other neurotransmitter systems (e.g., dopamine and serotonin) that interact with oxytocin and exert their own effects on social cognition. To address these critical gaps in knowledge, this research will use peripheral biomarker assay, neuropsychological assessment, and behavioral testing in a healthy community sample (N = 240, ages 20-80) to achieve four principle goals: (1) to characterize clinically-relevant patterns of psychosocial adjustment associated with endogenous oxytocin levels, (2) to map the developmental trajectory of oxytocin-dependent changes in psychosocial adjustment across stages of adulthood, (3) to test the moderating influence of specific cognitive and affective traits on oxytocin-mediated social cognitive processes, and (4) to validate 2-D liquid chromatography-tandem mass spectrometry as an ultra-sensitive technique for quantifying oxytocin level in human saliva. This new knowledge will aid our understanding of how oxytocin influences resilience toward psychosocial distress and provide much needed biomarker norms to assist practitioners in the optimization of oxytocin manipulation.